Exam Review Essays - Mechanics, Physics, Classical Mechanics

Exam Review UNIT 1 KINEMATICS Chapter 2: Describing Motion Acceleration / Time graph What does the vertical axis represent on an acceleration graph? The vertical axis represents the acceleration of the object. What does the slope represent on an acceleration graph? The slope of an acceleration graph represents a quantity called the jerk. The jerk is the rate of change of the acceleration. jerk= t / a What does the area represent on an acceleration graph? The area under an acceleration graph represents the change in velocity. In other words, the area under the acceleration graph for a certain time interval is equal to the change in velocity during that time interval. area= v Velocity / Time Graph What does the vertical axis represent on a velocity graph? The vertical axis represents the velocity of the object. This probably sounds obvious, but be forewarnedvelocity graphs are notoriously difficult to interpret. People get so used to finding velocity by determining the slopeas would be done with a position graphthey forget that for velocity graphs the value of the vertical axis is giving the velocity. What does the slope represent on a velocity graph? The slope of a velocity graph represents the acceleration of the object. So, the value of the slope at a particular time represents the acceleration of the object at that instant. slope= rise over run = v2-v1 divided by t2-t1 = t divided by v slope=acceleration What does the area under a velocity graph represent? The area under a velocity graph represents the displacement of the object. To see why, consider the following graph of motion that shows an object maintaining a constant velocity of 6 meters per second for a time of 5 seconds. Position / Time Graph What does the vertical axis represent on a position graph? The vertical axis represents the position of the object. For example, if you read the value of the graph below at a particular time you will get the position of the object in meters. What does the slope represent on a position graph? The slope of a position graph represents the velocity of the object. So the value of the slope at a particular time represents the velocity of the object at that instant. What does the curvature on a position graph mean? If a position graph is curved, the slope will be changing, which also means the velocity is changing. Changing velocity implies acceleration. So, curvature in a graph means the object is accelerating, changing velocity/slope . Frame of Reference : The different observations occur because the two observers are in different frames of reference . A frame of reference is a set of coordinates that can be used to determine positions and velocities of objects in that frame; different frames of reference move relative to one anothe r. Vectors and Scalars : Vectors have magnitude and direction, scalars only have magnitude. Displacement: What does displacement mean? If an object moves relative to a reference framefor example, if a professor moves to the right relative to a whiteboard, or a passenger moves toward the rear of an airplanethen the object's position changes. This change in position is known as displacement. The word displacement implies that an object has moved, or has been displaced. Displacement is defined to be the change in position of an object. It can be defined mathematically with the following equation: Position : Where something is located Time Intervals : Durationofasegmentoftimewithoutreferencetowhent hetimeintervalbeginsorends Velocity - Velocity gives us information about the rate of change of your position, meaning how fast your position is changing per unit time. In physics, velocity is defined as the displacement divided by time where displacement is defined as the difference between your final and initial positions. V( ave ) = Delta D / Delta T Constant - When an object travels the same distance every second, the object is said to be moving with constant velocity . This means that the magnitude of the velocity (or speed) and the direction of the velocity both remain constant. Instantaneous - Instantaneous velocity , is simply the average velocity at a specific instant in time or over an infinitesimally small time interval. Average - average